mail.achcity.com has no NS records.
NS records for this zone are defined at achcity.com.
NS records for this zone are defined at achcity.com.
Question and response
Question
dig mail.achcity.com. NS
Answer
The response has no answer records.
Authority
achcity.com. 3600 SOA achcity.com. noc.achmail.ru. 2026012823 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0